Tesla's inventions first appear in Behemoth, but Tesla himself does not appear until Goliath. The Leviathan finds him stranded near the Tunguska River in Russia and using an electric fence to keep starving fighting bears away from himself and the Russians who are aiding him in his experiments. These experiments include taking film of the Tunguska area and searching for the piece of metal which caused the destruction. The area has been mysteriously destroyed and Tesla claims that the cause was Goliath. When the Leviathan tries to take him on board, he suggest leaving some of the Russian men behind to have room on the Leviathan for his samples, and when he is attacked by bears he uses an electrical walking stick to protect himself from them.

The Leviathan carries Tesla to Tokyo, where he demontrates that the machine Goliath in New York can change the color of the sky in London. Alek decides that he and his men should join Tesla in order to end the war. Tesla travels with the

Leviathan to New York, where he plans to demostrate the same trick in Berlin before he threatens to destroy it, demanding that Germany surrender and end the war. When Goliath is attacked by a water-walker, Telsa plans to destroy Berlin with Goliath without giving warning to the people there or allowing the Leviathan time to leave the area and escape a fiery destruction. Alek fears for Deryn's safety and kills Tesla with the electrical walking stick to prevent him from firing Goliath.

He is an eccentric man who loves pigeons and choosing wines for dinner. Tesla believes that it is better to use Clanker technology in warfare rather than Darwinist technology because machines cannot feel pain in battle. However, when he is stranded in Russia he feeds fighting bears a Darwinist airship so that the bears will be distracted from eating humans. He often values scientific advancement more than human or animal life, and believes that he is very important for scientific advancement, although he is seen to be humanitarian, saying that, "To destroy a whole city... It's the most horrible thing any human could conceive." Dr. Barlow says that Tesla believes in martians. He isn't modest about his own genius, and believes that it is his duty to stop the war with Goliath and that he has the right to sacrifice anything for the greater good.